低成本海水改性生物炭颗粒的制备及其对水中磷的动态吸附性能

Fabrication of low-cost seawater-modified biochar granule and its dynamic adsorption performance for phosphate in aqueous solution

针对生物炭除磷领域中缺乏兼具经济性和实用性的Mg改性生物炭的问题,以海水为廉价Mg源,制备了海水改性生物炭颗粒(SBC-g),探究了其物理化学特性和吸附磷酸盐机理,考察了柱高、流量和初始质量浓度对SBC-g动态吸附磷酸盐的影响及对含磷养殖尾水的处理效果,并对SBC-g进行了经济性分析。结果表明,改性后SBC-g表面负载的Mg(OH)_(2)纳米片可增加吸附的活性位点,增大了介孔的孔径和孔容,改变了表面电荷性质,从而提高了其对磷酸盐的吸附容量。在一定范围内,柱高的增加或流量和初始质量浓度的降低均可延长穿透时间。Thomas模型对穿透曲线拟合良好(R2>0.919),可以较为准确地反映动态吸附过程。SBC-g吸附柱对养殖尾水具有良好的除磷效果,在最佳条件下吸附柱的穿透时间为589 min,磷饱和吸附量为1051 mg·kg^(-1)。SBC-g的生产成本约为2.65元·kg^(-1),和其他除磷吸附剂相比具有较大的价格优势,兼具经济性和实用性。该研究结果可为Mg改性生物炭的制备及其在水体磷污染治理领域的实际应用提供参考。

There is a lack of low-cost and easy-operation Mg-modified biochar in the field of phosphorus removal by biochar, and thus seawater-modified biochar granule(SBC-g) was prepared using seawater as a cheap Mg source. The physicochemical properties of SBC-g and mechanism of phosphate adsorption were investigated. The effects of column height, flow rate and initial concentration on the dynamic adsorption of phosphate by SBC-g, as well as the removal performance of phosphorus from aquaculture tail water, were studied. Finally, the economic analysis of SBC-g was carried out. The results showed that the Mg(OH)_(2) nanosheets loading on the surface of SBC-g after modification increased the active sites, enlarged the mesopore size and volume, and changed the surface charge properties, thereby increasing the adsorption capacity for phosphate. Within a certain range, the increase of column height or the decrease of flow rate and initial concentration could prolong the breakthrough time. The Thomas model fitted well with the breakthrough curve(R~2 > 0.919), which could accurately reflect the dynamic adsorption process. The SBC-g-loaded adsorption column exhibited a good performance on phosphorus removal from the aquaculture tail water. Under the optimal conditions, the breakthrough time was 589 min, and the saturated adsorption capacity of phosphorus reached 1051 mg·kg^(-1). The production cost of SBC-g was about 2.65 ￥·kg^(-1), which had a great price advantage against other phosphorus removal adsorbents, and thus SBC-g could be regarded as a low-cost and easy-operation adsorbent. The results of this study can provide a reference for the preparation of low-cost and easy-operation Mg-modified biochar and its practical application in the field of phosphorus pollution control for waterbodies.